Camelina: Long-term cropping systems research in a dry Mediterranean climate

Camelina [Camelina saliva (L.) Crantz] is a short-season annual oilseed crop in the Brassicaceae family. Interest in camelina has increased substantially during the past 15 years because the oil is an excellent feedstock for producing low-carbon-emission biofuel and has a unique fatty acid profile as a potential edible oil. Camelina has been promoted as an alternative crop in low-precipitation dryland regions because of its low fertilizer requirement and drought tolerance. An 8-yr field experiment was conducted from 2010 to 2017 at the WSU Dryland Research Station near Lind, WA to compare a 3-yr winter wheat (WW)-spring camelina-summer fallow (SF) rotation with the traditional 2-yr WW-SF rotation. Annual crop-year (Sept. 1-Aug. 31) precipitation ranged from 193 to 375 mm and averaged 281 mm. Camelina seed yield ranged from 339 to 1175 kg/ha and averaged 643 kg/ha. Mean WW yield of 2692 kg/ha in the 3-yr rotation was significantly lower (p = 0.046) compared to 2862 kg/ha in the 2-yr rotation. Soil profile water was significantly lower (p < 0.001) after harvest of camelina compared to after WW harvest in the 2-yr rotation. This soil water reduction was consistently measured throughout the ensuing 13-month fallow cycle. There are no labeled in-crop broadleaf weed herbicides for camelina and populations of Russian thistle (Salsola tragus L.) and tumble mustard (Sisymbrium altissimum L) were higher in camelina than in WW. This was likely a factor in the deep extraction of soil water in the camelina plots to a depth of 180 cm. Data from this study suggest that, with current cultivars and management practices, camelina is not yet agronomically or economically stable or viable in a 3-yr WW-camelina-SF rotation in the low-precipitation (< 300 mm annual) rainfed cropping region of the Inland Pacific Northwest (PNW).